According to the formulation of the present ubiquitous network-related standards and researches in the industry, it is universally acknowledged that the whole ubiquitous network coordination architecture is divided into a perception extension layer, a network/service layer and an application layer. There are many kinds of terminals in the perception extension layer and the application layer, and these terminal devices may be generally divided into two types. One type of terminal devices is a terminal group managed by a gateway in a unified manner, in which devices are intercommunicated through various protocols including a Universal Plug and Play (UPNP) protocol and access to a network through the gateway. The other type of terminal devices is a terminal group, which consists of intelligent terminals including user Personal Computers (PCs) and smart phones and may be accessed to a network directly.
For the terminal group consisting of intelligent terminals including user PCs and smart phones, if some terminals request to download the same media service, service requests of terminal users requesting for downloading may be accomplished by means of multicast rapidly and conveniently. Most conventional Internet Protocol (IP) multicast modes are applied to real-time service scenarios, such as multipoint conference, media broadcast and condition monitoring. If a new member joins in a service transmission process, the new member must have learned conditions of the multicast group and related members thereof and is incapable of acquiring service flows that have been transmitted previously. In a ubiquitous network coordination environment, the conventional IP multicast modes cannot be applied due to the heterogeneity of networks and terminals. The major problem lies in that a user cannot acquire a media multicast service in the case of being unable to learn the surrounding multicast group situation. In addition, for a terminal device joined during a multicast process, the user cannot acquire, by way of compensation, a service flow transmitted previously and fails to acquire more network capacity by using the characteristic of multiple modes and multiple interfaces of the terminal.